1. Field of the Invention
The invention relates to seal ring systems for a hydraulic apparatus, and more particularly, to composite seal ring systems.
2. Discussion of the Prior Art
Conventional O-rings in chevron type packings of the type employed in a hydraulic apparatus have recently been replaced by multiple-element sealing arrangements having both deformable and nondeformable components. These multiple component systems work especially well in high pressure applications. In such systems, a gland typically contains a three-part seal in which a wear-resistant plastic ring makes contact with a moving shaft. A deformable resilient ring may be disposed between the contact ring and the gland walls so that pressure applied to the deformable ring results in contact of the wear-resistant rings against the moving surface. U.S. Pat. Nos. 2,513,533, 3,817,517 and 3,394,941 disclose seal assemblies in which elastomeric rings bear against wear-resistant plastic rings which make contact with reciprocating cylindrical structures. These assemblies, however, all use a single contact ring. Applicant's improvement provides an elastomeric ring and two contact rings, a bearing ring and a backup seal ring. Pressure applied to the bearing ring enhances contact by the backup seal ring to provide a high pressure dynamic seal.